We are attempting to utilize the unique features of the small Bacillus subtilis phase Phi 29 in studies designed to define and analyze the steps involved in in vivo morphogenesis of this virus. Since a complete understanding of morphogenesis requires integrated analysis of the structure, function and expression of various genes, as well as direct studies on the assembly of gene products, we have initiated a coordinated investigation of these problems with the following specific aims: 1) To extend, confirm and eventually complete the mapping of the Phi 29 genome; 2) To continue studies on the structure of Phi 29 DNA, including fractionation, analysis of transfection and gene transfer by marker rescue, and determination of the nature and extent of terminal repetition; 3) To utilize the Phi 29 ts and sus mutants and specific DNA fragments for analysis of morphogenesis, including details of gene function, gene expression, and viral assembly.